The field of the invention is steel doors and the invention relates more particularly to commercial rolling doors which are held by a barrel at the upper end thereof and are opened by rolling the same up on the barrel. Such doors are fabricated from a plurality of steel slats, each slat having an upper curved channel which surrounds the lower curved portion of the adjacent superior slat.
Typically, such slats are held together by end locks riveted to alternate slats. Such end locks are riveted to the central portion of each slat and extend both upwardly to cover the intersection at the top of the slat to which it is riveted and downwardly to extend past the intersection of the lower end of the slat to which it is riveted. In this manner, the slats cannot be moved horizontally with repsect to each other because the lower end portion of one slat will abut the end lock which is riveted to the slat below it. Similarly, the upper end of the slat will abut the end lock which is riveted to the slat above it. The end locks ride in a channel and are capable of guiding the rolling door within the channel.
Such end locks have several shortcomings. Firstly, they are relatively large and add unnecessarily to the weight of the door. Secondly, they are labor-intensive to install in that holes must be punched or drilled in each slat to which they are affixed and the rivets or bolts pass through such holes into the end locks. Furthermore, since such end locks are typically made of cast iron, they tend to wear against the channels in which they ride. Such wear can form a groove into the channel and sometimes wear completely through the channel.
Another feature of typical rolling doors is a barrel to which the top of the door is affixed. This barrel surrounds a counter-balancing torsion spring which has a finite life. When the spring breaks or becomes detached at either end, it must be serviced. Such service is very labor-intensive, requiring many hours of cutting and welding on the job to accomplish.